A male who flaunts his erect penis to the annoyance of other males present. If you're about 14 and have a big cock for your age this is a good way to embarrass your classmates and make yourself feel even bigger. However, if you haven't grown out of this kind of behaviour by 18 then there's something wrong with you. You can go up to someone in the shower and say "hey, look at my big cock", or you can try to be subtle and get them to look by saying "hey, look at this bruise on my elbow" while pretending, implausibly, that you haven't even noticed that your cock is so hard that it's made your voice go husky. People who do this are probably not really gay, but they have to get used to being called it. Ways of dealing with a showcock include: 1. Pretend you haven't noticed. 2. Laugh at him. 3. Force him to back off by thrusting at him with your own giant erection. 4. If you think he's more scared of looking gay than you are then you could kneel down and pretend you're about to fellate him, but this is risky as you'll probably get cockslapped and if the teacher happens to walk past and glance in at this moment it can be very embarrassing for everyone involved, even bystanders. Note that a true showcock flaunts a fully erect penis, not a semi pretending to be flaccid, and he does it to males, not females, and he does it to fuck with them metaphorically, not literally. This is not a way to win friends and influence people.

Fuck off, you fucking showcock.

Miles is the worst showcock. He even gets his cock out during break.

Girl: You're not exactly shy.
Boy: Yeah, well, I used to be a bit of a showcock.
Girl: What's that?
Boy: You don't want to know. I mean ... nothing, really.